The present disclosure relates generally to information handling systems, and more particularly to techniques for integrating AC-to-DC adapter and battery charger devices commonly used to provide power to portable information handling system components such as notebook computers, personal digital assistants (PDA), cellular phones and gaming consoles.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system (IHS) generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
A battery converts chemical energy within its material constituents into electrical energy in the process of discharging. A rechargeable battery is generally returned to its original charged state (or substantially close to it) by a charging process such as by passing an electrical current in the opposite direction to that of the discharge. Presently well known rechargeable battery technologies include Lithium Ion (LiON), Nickel Cadmium (NiCd), and Nickel Metal Hydride (NiMH). In the past, the rechargeable batteries (also known as “dumb” batteries) provided an unpredictable source of power for the portable devices, since typically, a user of the device powered by the battery had no reliable advance warning that the energy supplied by the rechargeable battery was about to run out.
Today, through the development of “smart” or “intelligent” battery packs, batteries have become a more reliable source of power by providing information to the IHS and eventually to a user as to the state of charge, as well as a wealth of other information. The “smart rechargeable battery”, which is well known, is typically equipped with electronic circuitry to monitor and control the operation of the battery. A smart battery system, which typically includes at least one smart battery, is operable to provide power to a portable device.
FIG. 1 illustrates a typical multi-tier power supply system 100 operable to provide power to a load (not shown), according to prior art. Typically, the power supply system 100 receives and converts an alternating current (AC) power input 110 to a direct current power (DC) output 120 to power the load such as a portable IHS device 101 or components thereof. Traditional power supply systems utilize a two-stage power conversion process. The AC power input 110 is generally received from a 120 V, 60 hertz or 220 V, 50 hertz signal source from a wall outlet 105.
An AC-DC adaptor 130 included in the power supply system 100 forms the first stage of the two-stage conversion process. The AC-DC adaptor 130 converts the AC voltage input 110 to a first DC voltage output 115 to provide DC power to a system power rail block 140 and a charger device 150. The system power rail block 140 provides DC power to one or more DC-DC converters and other components of the IHS device 101.
The first DC voltage output 115, which is input to the system power rail block 140 is nominally set to approximately 19.6 V, which is sufficiently high to charge a battery 160, included in the power supply system 100, to a fully charged state. The AC-DC adaptor 130 typically utilizes a well-known ‘buck converter’ design (not shown) for the power conversion.
The second-stage of the power conversion process generally includes at least one DC-DC converter (also referred to as a regulator). The charger device 150, included in the power supply system 100, typically forms the second-stage of the power conversion process. The charger device 150 generally converts the first DC voltage output 115 of the AC-DC adaptor 130 to a lower DC voltage 119 suitable to charge the battery 160 included in the power supply system 100.
The system power rail block 140 and the battery 160 select the DC voltage output 120 to provide power to other downstream components of the IHS device. Power supply systems may utilize a plurality of DC-DC converters to convert the DC voltage output 120 of the power supply system 100 to multiple DC voltage levels of varying value. For example, in one application, a DC-DC converter 170 providing power to a processor 175 of the portable IHS device forms another stage of the power conversion process. This DC-DC converter 170 converts a battery voltage of approximately 12 VDC to a processor voltage of approximately 1.5 VDC. Other individual components (not shown) of the IHS device 101 may require other voltage levels.
A controller (not shown) included in the portable IHS device 101 is used for controlling the selection and operation of the battery 160 and AC power source 105 using various switches (not shown). Thus, the controller operating in conjunction with the battery 160, and the charger 150 controls the charging and discharging operation of the battery 160, as well as flow of power from the source 105 to a load, e.g., the device 101 by controlling the operation of these switches. The controller may control the battery 160 and the charger 150 via well-known System Management Bus (SMBus) (not shown), and/or via dedicated, electrically conducting lines or paths.
Voltage required to charge a battery may vary depending on the manufacturer. For example, Dell Computer Corporation (Round Rock, Tex., USA) provides 4 Series & 3 Series smart batteries for use in notebook computers such as a Dell Lattitude™ D-Series dual battery notebook computer. The 4SXP smart battery has a stack voltage of approximately (12V-16.8V) and the 3SXP smart battery has a stack voltage of approximately (9V-12.6V). The trend is towards the development of newer batteries having a lower stack voltage such as approximately (6-9V).
Power consumed by the processor 175 is increasing from one technology generation to the next. The supply voltage required by the processor 175 is also decreasing and is anticipated to fall below 1 Volt. The combination of lower voltages and higher currents make voltage regulation a more challenging task. One approach to improved voltage regulation is to narrow the voltage range of the charger device voltage output. This approach, however, often results in increasing the size and complexity of the charger device located within the portable IHS device, which often results in increased board space and thermal cooling requirements. In addition, this approach will result in a 3-stage power conversion process, e.g., AC-DC adapter 130 to the charger 150 to downstream regulators such as the DC-DC converter 170.
As described earlier, present power supply systems have a multi-tier power conversion architecture. This multi-tiered approach to power conversion is inefficient, increases heat dissipation, and reduces the amount of time the portable device may be used in a battery-operated mode. The high voltage of the AC-DC adaptor 130 generally results in poor efficiency due to low duty cycles, resulting in higher than desired switching losses. Power losses at each power conversion stage also result in costly thermal solutions and increased system skin temperatures. DC-DC regulators generally cannot be optimized for battery operation given thermal limitations when operating from the AC-DC adapter 130. To account for these power conversion losses, the AC-DC adapter 130 capacity is generally increased thereby driving up the adapter size and cost.
Therefore, a need exists to develop techniques for improving the efficiency of power conversion devices commonly used to provide power to portable IHS components. More specifically, a need exist to develop an efficient power conversion architecture that is less expensive and more reliable than such systems and methods heretofore available. Accordingly, it would be desirable to provide tools and techniques for integrating power conversion devices such as the AC-DC adapter 130 and the charger device 150 included in an IHS absent the disadvantages found in the prior methods and systems discussed above.